1. field of the Invention PA1 2. Prior Art
The present invention relates to a boat propulsion system in which a radially vaned rotor functions as the impeller of a centrifugal pump when the boat is traveling at low speed and as a paddle wheel when the boat is traveling at high speed.
Paddle wheel boat propulsion systems are usually of simple design and construction. Representative paddle wheel systems are shown in the following U.S. Pat. Nos.: Connison--2,672; Aldrich--2,709; Weber--1,241,065; Moore--4,004,544.
Centrifugal pump boat propulsion systems are more complex than paddle wheel systems but are particularly efficient at low speeds. Such systems are shown in the following U.S. Pat. Nos.: Burgin--3,128,740; Davis--3,348,514.
No boat propulsion system is known in which a radially vaned rotor functions as the impeller of a centrifugal pump at low boat speeds and as a paddle wheel at high boat speeds. More specifically, in no known paddle wheel system has a paddle wheel been mounted in a housing having an axial water inlet and a peripheral outlet so that the paddle wheel can function as the impeller of a centrifugal pump. Similarly, no centrifugal pump propulsion system is known in which an impeller is mounted for rotation about a horiziontal axis extending athwartships of a boat with the tips of the impeller vanes projecting below the water through a downwardly directed peripheral opening in the pump housing so that the impeller can function as a paddle wheel.